In some individuals, one or more heart valves may not function normally, typically as a result of disease-induced valve damage, degeneration, or a congenital defect. Valve dysfunction can include valve regurgitation, which can be a life-threatening condition. One method for treating valve dysfunction is valve replacement with one of a variety of replacement valve types. Such replacement heart valves may be relatively rigid or may be flexible, and may be generally categorized into one of two primary classes of replacement heart valves. The first class includes valves commonly referred to as a mechanical prostheses, which typically have one or more relatively rigid leaflets formed of a stiff biocompatible material and/or which include commisures that are self-supporting, and do not need to be affixed to an adjacent structure. Mechanical prostheses are generally formed of artificial materials and rigidities which may be easily handled during surgery, but are more prone to thrombogenesis, and therefore typically require prolonged anti-coagulation therapy.
The second class of replacement heart valves is bioprosthetic or biologic valves, which are typically flexible and may be made of a biological material. This category includes valves harvested from human cadavers (allografts or homografts) or animal tissue (xenografts). More recently, however, flexible replacement valves made of synthetic biologically compatible materials have been developed as substitutes for such natural tissues. Bioprosthetic valves typically do not require lifelong anti-coagulation therapy, as such materials do not often lead to clot formation.
Flexible replacement heart valves, such as flexible bioprosthetic valves may be stented or unstented. A stented valve includes a frame for configurationally supporting the replacement valve, and particularly its commisures, at least in the implantation procedure. Such frames may be permanently or removably secured to the replacement valve. Unstented replacement valves do not include commisure support members to configurationally maintain the replacement valves during implantation, and potentially further in permanent use. The frames may take the form of a wire or other metal or plastic framework which supports the flexible valve material. While stented valves provide a relatively stable and self-supporting structure to facilitate proper implantation and alignment of the commisures, the stent frames can result in narrowing of the valve orifice, and can also cause significant stresses on the commisures during valvular operation. Such stresses can lead to valve degradation and dysfunction.
Unstented valves do not have the drawbacks described above with respect to stented valves. However, unstented valves do not have commisure support, such that implantation of the valve requires a more exacting surgical procedure to properly orient the annulus and commisures at the implantation site. In particular, the surgeon must secure each individual commisure in a precise and correct orientation in order to allow the replacement valve to properly function. Due to the flexible structure of the bioprosthetic valves, such placement and securement is difficult.
In an aortic replacement valve, for example, the commisures must be substantially equally spaced at about 120° apart both at their upper and lower ends. Moreover, the commisures should be substantially perpendicular with respect to the annulus plane. Few devices are currently available to aid the surgeon in correctly orienting the replacement valves in the implantation procedure. In particular, devices are not currently available for maintaining the replacement bioprosthetic valve in a correct orientation and shape while the surgeon secures such replacement valve in an appropriate coronary sinus.
It is therefore a principal object of the present invention to provide an implant holder device which maintains an implant, such as an unstented bioprosthetic heart valve, in a correct orientation and shape during the implantation procedure.
It is a further object of the present invention to provide an implant holder which operably retains the implant in a correct implantation orientation and shape while disposed externally to the implant.
It is a still further object of the present invention to provide an implant holder which enables full installation of the implant while the holder remains secured to the implant.